Since the improvement of the computer and digital technologies, many created contents (such as movies or music, etc.) may be converted into digital forms of audio and/or video compression files. Subsequently, the files may be burned, or recorded, to portable data storage media such as CDs or DVDs, or other audio/video (A/V) carriers for playing back. Other than movies and music, the contents may include speech contents, teaching contents, opera contents, etc. All these contents may be converted into digital A/V compression files (hereinafter referred to as digital data).
However, due to the progress of compression and duplication technologies, all contents can be easily converted into file formats which can be easily copied by various duplication or burning technologies. With the prevalence of networks, digital contents can be widely distributed by being uploaded to networks and downloaded from networks. As the intellectual assets of creators of such contents cannot be well protected due to new duplication technologies, the will for creativity may be suppressed. Therefore, there is an eager demand for a novel technology to prevent the digital contents from being copied when copying is not permitted, so as to protect the intellectual assets of musicians, publishers, actors, and the like, and to match the requirement of intellectual property laws.
In generally, currently most portable data storage media for carrying digital data are in the forms of discs such as CDs and DVDs. Other than some less commonly used erasable optical discs which can be burnt many times, most carriers cannot be burnt repeatedly. Since these portable data storage media have large volumes, in many currently available players (such as MP3), the digital data are copied to memory cards (for example, SD cards) for use.
Current memory cards are mainly used to store the digital data and thus have the same use as discs. If a memory card can be used as a digital data carriers having the security features of secured digital (SD) card and small form factor, then it makes a preferable digital data carrier and can be carried easily and widely used with security function for the protection of the data stored therein. Other than high transmission speed and large capacity, the SD memory cards currently available are relatively inexpensive to be accepted by the market. Thus, the time of memory cards as the choice for digital data carriers has come.
Typically, digital rights management (DRM) in a personal computer (PC), for example, can provide security in data transfer for downloading digital data through a network as the user pays a fee for downloading the digital data without fear of the downloaded data being copied or spread illegally. DRM can also be used to confine the times, identifies, time periods and the number of copies for duplication of the download contents. Nevertheless, current DRM techniques cannot provide data security for the data stored on portable data storage media (especially in the case of memory cards).